Background: Justice-involved Veterans ? military Veterans detained by or under the supervision of the criminal justice system ? have an excess burden of mental health and medical morbidity, as well as elevated mortality risk compared to the general and Veteran populations. Despite high rates of use of mental health and substance use disorder treatment, justice-involved Veterans are at risk for receiving lower quality mental health and addiction treatment. Furthermore, the quality of their medical care has never been examined despite their heightened risk for disparities. By examining patterns in quality of care, identifying patient, provider, and health system factors related to high and low quality of care, and hearing from justice-involved Veterans and VA staff about barriers to and facilitators of high quality care, we can develop new quality improvement initiatives to improve care for this vulnerable population. Objectives: Specific aims are to: (1) Determine whether justice-involvement is an independent risk factor for poor care quality; (2) Identify predictors of care quality among justice-involved Veterans; and (3) Evaluate Veterans' and other stakeholders' perceptions of factors that explain variation in quality of care. Methods: The proposal project is guided by the Behavioral Model for Vulnerable Populations. Aim 1 uses existing VHA administrative databases and established process quality measures to examine whether being justice-involved is independently associated with lower quality of care. We will focus on major causes of morbidity and mortality in this population, including substance use disorders, mental health disorders, hypertension, hepatitis C, HIV, and colorectal cancer. Aim 2 uses existing VHA administrative databases to identify predictors of high or low quality of care among justice-involved Veterans. Secondary analyses will examine a subset of Veterans who have more detailed data collected during justice outreach. In Aim 3, we will conduct 80 qualitative interviews total with justice-involved Veterans and VHA justice outreach staff, clinicians, and managers. The Consolidated Framework for Implementation Research will guide qualitative data collection, coding and analysis. Summary: This study will serve as the foundation for future studies that address barriers to and implement drivers of high quality care across VHA facilities. Accomplishing these aims will help us understand and improve the quality of care received by some of our most vulnerable Veterans, improve their health, and decrease their risks for hospitalizations and mortality.